Spiral striped insulator conductor and spiral striping means



April 14, 1970 w, BR D 3,505,916

SPIRAL STRIPED INSULATOR CONDUCTOR AND SPIRAL STRIPING MEANS Filed May 15, 1968 2 Sheets-Sheet 1 INVENTOR.

2016 26' 15- 4 i/ziiw/g i April 14,1970 A. WQBRANDT 3,505,916

SPIRAL STRIPED INSIILATOR CONDUCTOR AND SPIRAL STRIPING MEANS 2 Sheets-Sheet 2 Filed May 15. 1968 INVENTOR.

Us. or. 82-54 ,5 16 SPIRAL STRIPED INSULATOR CONDUCTOR AND SPIRAL STRIPING MEANS Adolph W. Brandt, 124 Los Angeles Ave., Stratford, Conn. 06497 Filed May 15, 1968, Ser. No. 729,248

Int. Cl. B23b 3/06 7 5 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to a novel spiral striped insulated conductor and to a method and apparatus for marking the insulated conductor for identification. More particularly, the apparatus aspect of this invention relates to. a heated striping die for cutting continuous spiral grooves through a layer of insulation at extrusion speeds.

Multiple conductor communication cables such as those used in the telephone industry comprise a multiplicity of conductor pairs each of which carry a separate telephone circuit. In the past the individual conductive wires have been insulated with a coat of paper applied helically or laid down on the wire as a pulp, which solidifies thereon. These known methods of insulating electrical conductors with paper are relatively slow. Therefore, most recently, thermoplastic insulating. coatings, such as polyethylene, have been applied to electrical conductors by being extruded thereon at extremely high linear speedsve.g. 1500 to.-2000. feet per minute. Polyethylene is also more desirable than paper because of itsexcellent electrical properties including its low dielectric constant and its imperviousness to water and water vapor. Furthermore, by the simple addition of pigments to the polyethylene granules in the extruder a wide variety of color coded insulated coatings are possible.

. s described above, the conductors of a multiple conductor communication cable are utilized in pairswhich are generallytwisted together. In .order to identify the two conductors of a single pair the insulation is color coded for cross-identification. Initially, each conductor was coated with insulation of a single color and eachpair comprised a known combination of colored conductors. Of curse, the number of combinations was limited and it was not uncommon to find several similarly identified pairs in a multiple conductor cable. In order to increase the number of colorcombinations it has recently been the praetiee to provide the single colored insulations with a stripe or other design of a contrasting color. Generally, the contrasting colored material is an ink which is brushed on the surface of the rapidly moving insulated conductor. To, form a spiral stripe which is a common marking, ink is: applied onjone Side of the moving conductor by means of a first brush and to the other side thereof by means of a 'second brush. A major disadvantage of the known inking methods is theirunreliability resulting in spotty markings.

United States Patent 0 3,505,916 Patented Apr. 14, 1970 SUMMARY OF THE INVENTION Accordingly, it is the primary object of my invention to provide an inexpensive and reliable means for spiral striping a thermoplastic insulated conductor by cutting away a portion of the insulation with an electrically heated striping die.

Another object of my invention is to provide a spiral striped double-coated insulated conductor in which each coat has a diiferent appearance and the outer coat is spirally cut to reveal the inner coat.

Another object of my invention is to provide a crossidentified pair of insulated conductors each formed in accordance with my invention wherein the pair has improved electrical properties.

To accomplish the primary object of my invention, in one form I have provided a spiral striping die for marking a continuously moving insulated conductor including a first rotatable member coaxial with and surrounding the insulated conductor and a second rotatable member coaxial with both the insulated conductor and the first rotatable member and axially spaced from the first rotatable member. First and second electrically conductive rings are mounted upon the facing ends of the first and second rotatable members and an electrically heatable wire is secured to and between the first and second rings being biased against the central axially moving insulated conductor. A pair of electrically conductive shoes in continuous sliding engagement with the first and second electrically conductive rings are connected in a circuit with an electric power source. The rotatable members are connected with a suitable gear train to drive them synchronously.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and further details of that which I believe to be novel and my invention will be clear from the following description and claims taken with the accompanying drawings wherein:

FIG. 1 is a perspective view of a portion of a multiple conductor communication cable showing several conductor pairs;

FIG. 2 is an enlarged perspective view partially in cross-section showing a single twisted conductor pair;

FIG. 3 is a perspective view of a spiral striped conductor made in accordance with the method of this invention;

FIG. 4 is a plan view of the striping apparatus of my invention; and

FIG. 5 is a sectional view taken substantially along line 5-5 of FIG. 4.

DESCRIPTION OF THE IMPROVED ARTICLE Turning now to the drawings there is illustrated in FIG. 1 a multiple conductor'communication cable which may be, for example, a telephone cable generally designated by the numeral 10. The cable 10 includes an inner core assembly made up primarily ofa multiplicity of twisted conductor pairs 12, each of which may form a separate telephone circuit. Encircling the conductor pairs is an outer layer of insulation 14 which may be of any suitable type.

A single conductor pair 12' is shown enlarged in FIG. 2 and a single conductor 16 is illustrated in FIG. 3. Each conductor 16 comprises a central axial wire 18 surrounded by a base layer 20 of plastic insulation material such as polyethylene, polyvinyl, Teflon (a trademark of Du Pont) or other suitable material, and -a substantially thinner outer layer 22 of plastic insulation material which is the same as or is compatible with the base layer. Polyethylene is preferred as it has extremely good self adhering characteristics. The two layers of insulation material may be applied to the i-Wire 18 in a known manner as it is continuously passed through primary and secondary extrusion heads. The insulation material of each layer is of a different color for color coding purposes, as will become apparent.

It should be noted that a spiral groove 24 is cut into the conductor 16, the cut passing completely through-the outer layer 22 and exposing the base layer 20 which is of a contrasting color. By accurately controlling both the thickness of the outer layer and the depth of the cut, the visibility of the contrasting colored base layer is insured. This enables simple cross-identification of mating conductor pairs. For example, one of the conductors may have a blue base layer and a yellow outer layer which, when grooved, will appear as a blue-striped yellow' conductor. Its mate would be formed with a yellow base layer and a blue outer layer and when grooved would appear as a yellow-striped blue conductor. It would also be possible to mate a striped and solid conductor if so desired.

With reference to the twisted conductor pair illustrated in FIG. 2 the two conductors are referred to as 16a and 16b for clarity. It should be noted that the groove 240 formed in conductor 16a is arranged in a clockwise path Whereas the groove 24b formed in its mate 16b is arranged in a counterclockwise path. In this manner, when the conductors are twisted together, pockets of air 26 are captured between the conductors at the intersections of the grooves 24a and 24b. As air is being substituted for plastic insulation material at regular intervals and forms some of the dielectric insulation in the pair, the combined dielectric constant is lower than that of the plastic insulation alone. Therefore, it should be apparent to those skilled in this art that I have not only provided an improved color coded insulated conductor but that I have also provided a conductor pair having improved electrical insulating properties.

DESCRIPTION OF THE PREFERRED STRIPING APPARATUS In FIGS. 4 and 5 there is illustrated the preferred form of the striping apparatus of my invention which is utilized to form the spiral striped insulated conductor 16 described above. The apparatus, generally referred to by the numeral 28, is supported above a suitable frame 30 upon upright standards 32. An insulated conductor is drawn through the apparatus at extrusion speeds by suitable driving means 34. Wire 18 to be insulated initially passes through a usual extrusion head (not shown) having a primary extruder which applies the base insulation layer 20 to the wire and'an auxiliary extruder which applies the outer insulation layer 22. From the extrusion head the wire passes through a water cooling trough and excess water is blown from the insulated conductor by means of a suitable air wipe. Then the insulated conductor passes to the striping apparatus 28 as shown in FIG. 4.

The striping apparatus comprises first and second rotatable spindles 36 and 38 mounted in the inner rings of anti-friction bearings 40 which are carried upon the upright standards 32; Supported within the bore 42 of each spindle is a sleeve 44 which is in the form of a tubular member having a bore 45 with a tapered entrance 46 at one end and an internal pipe tap 48 at its other end. The sleeve bore 45 is'slightly larger than the outer diameter of the insulated conductor and serves to guide the conductor. Therefore, it should be appreciated that sleeves having bores of different size are interchangeably mountable within the bore 42 of the spindles. A set screw 50 secures the sleeve 44 in position within the spindle bore.

Collars 52, made of a suitable non-conductive plastic material, tightly encircle the facing ends of the spindles 36 and 38 each collar having an electrically conductive metal ring 54, preferably made of copper, firmly mounted thereon. Electrically heatable cutting members 56 comprising electrically conductive rigid wires made of Monel or other suitable material are secured to the rings 54,

. "s tsoatue as by soldering, at substantially diametrally opposite locations. As the wires 56 must be taut to perform. their cutting operation there is a tendency for the firmly mounted collars 52 to become axially inwardly displaced. To retain the collars in position I have provided securing caps 58 each having a retaining flange 60 and a tubular axial extension 62 with pipe threads 64 formed on its outer diameter. When'the pipe threads'64 are threadedly engaged with'the pipe tap 48 of the sleeve 44, the flange (it) retains the collar on the spindle.

In continuous sliding engagement with the conductive metal rings 54 there are two stationary electrically conductive carbon shoes 66 mounted in corresponding fixtures 68 on standards 70 extending vertically upwardly from the frame 30. The shoes are electrically connected by insulated conductors 71 to a suitable voltage source. Thus, current may be passed from the first carbon shoe '66 to the first metal ring 54 and then through the cutting members 56 to the second ring 54 and to the second carbon shoe 66. By regulating the current passed through this circuit the cutting members 56 may be heated to various elevated temperatures.

It should be apparent that in order to form a spiralgroove in the insulated conductor it becomes necessary to rotate the first and second spindles at a rapid rate while heating the cutting members 56. Of course, the spindles 36 and 38 must be rotated at the same speed in order-to maintain a given fixed distance between the cutting members at their closest, i.e. central, points.

The driving arrangement I have devised for synchronous rotation of the first and second spindles includes a drive motor 72 having a drive shaft 74 with a drive gear 76 secured thereto. A first spindle gear 78 having a hub 80 in which is positioned a set screw 82 to retain the gear 78 on the spindle 36 is in engagement with a first connecting shaft spur gear 84 having a hub 86 and set screw 88 for securement upon a connecting shaft 90. The connecting shaft 90 extends parallel to the first and second spindles and is supported for free rotation in antifriction bearings 92 mounted upon standards 94. A second connecting shaft spur gear 96 similarly mounted is in driving engagement with a second spindle gear 98. Itshould be apparent that first and second spindle gears 78 and 98 must be the same size and similarly the first and second connecting shaft spur gears 84 and 96 must be the same size in order to achieve a one-to-one driving relationship between the spindles 36 and 38'.

In order to vary the depth of cut through the insulation layers and to spiral groove wires of different sizes it is necessary to establish the distance between the central points of the cutting members 56. This may be accomplished by loosening the set screw 82 and rotating the first spindle 36 relative to the stationary first spindle gear 78. It should be recalled that the second spindle 38 is held in a fixed position by the gear train and that depending upon the direction of rotation of the first spindle 36 the cutting members are either brought closer together or are moved further apart. When the desired distance has been established the set screw 82 maybe tightened and the spindles 36 and 38 may be synchronously rotated. l

I Operation of the apparatus 28 is as follows: The drivmg means 34 and motor 72 are energized and the circuit from the electrical power source through the carbon shoes 66 is closed. Thus, the insulated. conductor is drawn axially through the apparatus while the electrical- 1y heated cutting members 56 are rapidly rotated. As the heated cutting members rotate against the plastic insulation of the longitudinally moving conductor they melt away portions thereof, each member-56 cutting a spiral groove 24. By maintaining the proper. distance-between the central cutting portionsof the cutting members, regu- M lating their speed of rotation and regulating the current passing through the heating circuit, the

Having described my invention of an improved spiral striped insulated conductor and a unique spiral striping apparatus for forming the same it should be readily appreciated by those skilled in this art that an apparatus embodying my invention is simple in design, low in cost, and ingenious in operation. Furthermore, the marked conductor formed thereby is inexpensive and reliable to manufacture and has improved electrical insulating properties when mated with a similarly formed conductor pair.

It should be understood that the present disclosure has been made only by way of example and that numerous changes in details of construction and the combination and arrangement of parts may -be resorted to without departing from the true spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. A spiral striping die for marking a continuously moving insulated conductor, comprising: first rotatable means coaxial with the insulated conductor; second rotatable means coaxial with both the insulated conductor and said first rotatable means and axially spaced from said first rotatable means; first and second electrically conductive rings mounted upon the facing ends of said first and second rotatable means; electrically heatable cutting means secured to and between said first and sec-' ond rings, positioned against the central axially moving insulated conductor; a pair of electrically conductive shoes in continuous sliding engagement with said first and second electrically conductive rings; circuit means to connect said pair of shoes to an electric power-source; and driving means engaged with said first and second rotatable means to synchronously drive said rotatable means.

2. The spiral striping die defined in claim 1 wherein said first and second rotatable means each comprise: a tubular spindle; bearing means to support said spindle for rotation; and a sleeve, positioned in the bore of said tubular spindle, having a central axial passage slightly larger than the outer diameter of the insulated conductor which moves therethrough.

3. The spiral striping die defined in claim 1 wherein said electrically heatable cutting means comprises two wires each extending from one of said rings to a substantially diametrally opposed position on the other of said rings, whereby, angular adjustment of said first rotatable means relative to said second rotatable means moves the central cutting portions of said wires relative to one another for striping insulated conductors of various size.

4. The spiral striping die defined in claim 1 wherein said driving means comprises: a motor, a driving gear carried by said motor; a first gear, mounted upon said first rotatable means, in engagement with said driving gear; a second gear mounted upon said second rotatable means; a rotatable connecting shaft extending substantially parallel to said aligned first and second rotatable means; a first connecting shaft gear, carried by said connecting shaft, in engagement with said first gear; and a second connecting shaft gear, carried by said connecting shaft, in engagement with said second gear.

5. The spiral striping die defined in claim 4 wherein said first and second gears are of the same size and have the same number of teeth; and said first and second connecting shaft gears are of the same size and have the same number of teeth, whereby when said motor is energized the gear train will rotate said first and said second rotatable means at the same speed.

References Cited UNITED ST ATES- PATENTS 1,306,588 6/1919 France -8254 X 1,333,311 3/1920 Holz et al. 83170 X 1,687,872 10/1928 Maynard 83-470 2,109,437 2/1938 Shook 83170 2,334,577 11/1943 Postlewaite 83170 X 2,425,123 8/1947 Quayle et a1. 83170 2,916,595 12/1959 Priestly 83171 3,052,142 9/1962 Simon 82--54 3,322,010 5/1967 Engel 83170 HARRISON L. HINSON, Primary Examiner US. Cl. X.R. 

